chemistry
posted by NIK .
N2O5 dissolved in CCl4 decomposes to give N2O4 and O2. The reaction is first order with a halflife of 1234 seconds. How long will it take, in seconds, for the concentration of N2O5 to fall to 1.1% of its initial value?

the fraction left after t seconds is (1/2)^(t/1234)
so, solve
(1/2)^(t/1234) = 0.011
t = 8028.84
makes sense: .011 is around 1/64, or 6 halflives 
t=8028.84

8028.84